如何在ubuntu中连接mysql和eclipse氧气答案

【问题标题】：how to connect mysql with eclipse oxygen in ubuntu如何在ubuntu中连接mysql和eclipse氧气
【发布时间】：2018-04-09 17:03:46
【问题描述】：

我正在尝试使用 eclipse 和 mysql 服务器使用下面的 java 代码创建 JDBC 连接

package dcv;

import java.sql.*;
public class testdb {

    public static void main(String[] args) {

          Connection con= null;
          try {
              Class.forName("com.mysql.jdbc.Driver");
                con = DriverManager.getConnection("jdbc:mysql://localhost:3306/sys", "root", "12345");
            } catch (Exception ex) {
            // TODO Auto-generated catch block
            System.out.println("Exception: "+ex);
    ex.printStackTrace();
        }
    }

}

但是在运行根名称和密码以及架构没有错误的类文件后出现如下错误，我正在使用 mysql-connector-java-5.1.30.jar 文件。

Exception: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server.
com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server.
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:409)
    at com.mysql.jdbc.Util.getInstance(Util.java:384)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1013)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:987)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:973)
    at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:918)
    at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2588)
    at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2321)
    at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:832)
    at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:409)
    at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:417)
    at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:344)
    at java.sql.DriverManager.getConnection(DriverManager.java:664)
    at java.sql.DriverManager.getConnection(DriverManager.java:247)
    at dcv.testdb.main(testdb.java:11)
Caused by: java.lang.NullPointerException
    at com.mysql.jdbc.ConnectionImpl.getServerCharacterEncoding(ConnectionImpl.java:3307)
    at com.mysql.jdbc.MysqlIO.sendConnectionAttributes(MysqlIO.java:1985)
    at com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1911)
    at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1288)
    at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2506)
    at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2539)
    ... 13 more

如何在我的 Ubuntu 操作系统中解决这个问题？

【问题讨论】：

升级到最新版本的 MySQL Connector/J (5.1.44) 是否有效。

标签： java mysql eclipse jdbc

【解决方案1】：

尝试 ping 您的数据库服务器，看看您是否能够连接。否则解决网络问题，然后连接。

以下是创建数据库连接的代码

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;


 DBConnection() throws SQLException, ClassNotFoundException {

            url = "jdbc:mysql://localhost/(your DB name)";

            user = "your user";

            password = "your password";

            Class.forName("com.mysql.jdbc.Driver");
            conn = DriverManager.getConnection(url, user, password);
        }

【讨论】：